Wylie is preparing 20 liters of an 18% solution. He has two other solutions with strenghts of 10% & 20%. Find the amount of the 10% & 20% solution if mixed to get 20 liters of an 18% solution?

x+y=20.

0.1x+0.2y=0.18*20.

=0.1x+0.2y=3.6.

0.1x+0.2(20-x)=3.6.

0.1x+4-0.2x=3.6.

0.1x=0.4.

x=0.4/0.1=4 litres.

y=20-x=20-4

=16 litres.

Amount of the 10% & 20% solution are 4, 16 Litres .